I believe this is set by the system you are on, have you dialed *228 to program the phone/update PRL?
Before I did *228 to program my home SID, my phone said "Digital Roaming" instead of "AllTel".
Be aware that there have been reports of *228 not working well with cricket flashed phones. You can keep trying, or just Grab this PRL file and manually update your phone:
Cricket 1040 PRL from MotoRAZR
Don't know if this will fix your specific problem though since Cricket shares towers pretty profusely.(ie: AllTel tower may BE your home SID)